The York Research Database

Sonic crystals have been presented previously as both a potential type of noise barrier, and as a form of sonic art aimed at enhancing the perception of an urban soundscape. Most simulations of such structures are evaluated based on a measure of Insertion Loss - the spectral attenuation imparted on a sound source due to the insertion of the structure under investigation between source and receiver. Although this gives an indication as to the noise attenuation performance for a barrier, it gives little qualitative information as to how results might be perceived when considered in the context of the soundscape in which a sonic crystal might be placed. This is particularly important if the device, through its design, is intended to enhance a given soundscape, rather than mitigate against its negative, or noisy, aspects. This paper presents a finite difference time domain simulation of a 2-D periodic structure suitable for use as a sonic crystal noise barrier. The impulse responses obtained from these simulations are used to filter typical audio source material recorded from an urban environment resulting in a number of auralisations that can be used to evaluate the effects of such structures on a typical soundscape. A perceivable difference listening test is used to determine how effective these 2-D periodic structures are at making a significant change in the source material. Results confirm that there are significant perceivable differences imparted due to the sonic crystal structures used, under the assumed limitations of these evaluations having taken place under laboratory conditions and where the duration of the source material does not exceed that of the average auditory short- term memory. Further work will explore whether these differences are significant under more natural listening conditions.